Money Flow Index (MFI) is a volume-based indicator it could be used in technical analysis to measure the strength of money flow in and out of a security index and market. The principle of MFI calculation is a comparison of positive money flow to negative money flow. MFI is also known as volume-weighted RSI. MFI starts with the typical price for each period. The same as RSI the MFI scale is between 0 and 100.